i6o 



HENRY A. PILSBRY. 



The same species ranges southward along the west coast to Echigo 

 and Matsue, Izumo. Here the shells are large and rounded, with very 

 full beaks, much eroded in adults. The exterior is black, the inside 

 whitish, blue-stained at the ends, and sometimes with a purple spot in the 

 beak-cavity. An old shell measures, length 40, alt. 36, diam. 27.5 mm. 

 These shells resemble the following variety in coloration. 



Corbicula nipponensis delicata n. subsp. Plate VII, fig. 11, 12. 



The shell is similar to C. nipponensis in general characters, but is 

 smaller and thinner, the hinge and nymphs narrower. Surface finely 

 striated, smooth at the beaks, blackish with several brown and black zones 

 and sometimes some black rays, usually not conspicuous. The interior 

 is light violet or whitish, paler in the middle, and marked with a purple or 

 violet spot in the cavity of the beaks. 



Length 25.5, alt. 24.8, diam. 14.8 mm. 



Imaegata, Kaga. 



This variety occurs also at Kahokugata, Kaga, uniform black 

 specimens, and at Tögöike, Hôki, where the shells are black, with the 

 interior bluish-white or violaceous-white, with a very conspicuous purple 

 spot in the cavity of the beaks. 



Explanation of Plate VII. 



Fig. I, 2. 

 t, 3» 4- 

 » 5. 6. 



Corbicula ortliodonta Pils. Owari. 



II, 12. 



Iß. 14 



IS, 16. 



17, 18. 



7, 8, 9, 10 



>» 



nif>ponensis „ . Kogawaranuma, Mutsu. 

 Icana Prime. Shikanjima, Osaka. 

 viola Pils. Chikumanaiko, Lake Biwa, 

 nipponensis delicata Pils. Iwaegata, Kaga. 

 azvajiensis Pils. Nöda, Awaji. 

 sadoensis ,, . Sado. 

 sandai Rcinh. Lake Biwa. 



